1,3,4-thiadiazine herbicides

ABSTRACT

New N-substituted derivatives of 2-amino-5-tert.butyl-6H-1,3,4thiadiazine are employed to combat undesired vegetation by both post- and pre-emergent application techniques, carbamyl substituted compounds are preferred.

D United States Patent 1 1 3,779,736

Doyle, Jr. 1 Dec. 18, 1973 1,3,4-THIADIAZINE HERBICIDES PrimaExaminer-James 0. Thomas Jr. 751 MW 0.1): .L d, a 1 men or g 0y Jr eawooAtt0rneyRichard L. Kelly, Carl A. Cline, Forrest D.

Stine and Howard F. Van Denburgh [73] Assignee: Gulf Research &Development Company, Pittsburgh, Pa.

[22] Filed: Jan. 4, 1971 [57] ABSTRACT [21] Appl. No.: 103,814

New N-substituted derivatives of 2-amino-5-tert.butyl- [52] US. Cl.71/90, 260/243 R 6H-l,3,4-thiadia2ine are employed to combat unde- [51]Int. Cl A0ln 9/12 sired vegetation by both postand pre-emergent appli-[58] Field of Search 71/90; 260/243 cation techniques, carbamylsubstituted compounds 1 are preferred. [56] References Cited UNITEDSTATES PATENTS 4 Claims, No Drawings 2,838,389 6/1958 Yoder 71/90 1Qfl'TBIAD INEHEKB Q E DESCRIPTION OF THE INVENTION in which R ishydrogen, methyl or ethyl and R is selected from the group consisting oflower N-alkyl or N- alkenyl carbamyl, lower N-alkenyl orN-alkylthiocarbamyl, C to C acyl and lower alkoxycarbonyl substituents.The novel compounds may be prepared from available starting materialsaccording to procedures of the type specifically exemplified below.

PROCEDURES FOR SYNTHESIS OF I-IERBICIDES PREPARATION OF2-AMlNO-5-TERT.BUTYL-6I-I- 1,3,4:TIIIADIAZINE V solid is collected byfiltration and is washed with hexane, givingN-methyl-N'-(5-tert.butyI-6H-l ,3,4- thiadiazin-2-yl)urea, m.p. 19l-3.In a similar manner the reaction of methyl isocyanate with theappropriate Z-aIkyIaminothiadiazine gives N,N-dimethyl-N-(5-tert.butyl-6H-l,3,4-thiadiazin-2-yl)urea and N-methyl-N'-ethyl-N-(S-tert.butyl-6I-I-I ,3,4-thiadiazin'2- PREPARATION OFN,N'-DIMETHYL-N-(5- TERT.BUTYL-6l-I-1,3,4-TI-IIADIAZIN-2- YL)THIOUREA Asolution of 21.5 g of 2-methylamino-- -tert.butyl-6H-1,3,4-thiadiazineand 6.7 g methyl isothiocyanat ein 56 rnl dioxane is heated to Fefluxfo?several hours and the solution is evaporated to dryness on a rotaryevaporator. The residue is dissolved in benzene and the benzene solutionis extracted with water, dried and evaporated, giving N,N'-dimethyl-N'-(5-tert. butyl-6H-1,3,4-thiadiazin-2-yl)thiourea as aviscous gum. PREPARATION OF Z-CHLOROACETAMIDO-S-TERT.BUTYL-6H-1,3,4-THIADIAZINE To a solution of 3.7 g of2-amino-5-tert.butyI-6H- 1,3,4-thiadiazine and 2.2 g triethylamine in 25ml dioxane is added dropwise 2.5 g of chloroacetyl chloride. Thesolution is stirred several hours, poured into water and the resultantprecipitate filtered, washed with water and air dried to give2-chl0roacetamido-5- tert.butyl-6H-l,3,4-thiadiazine, m.p. 158-9.

Using procedures similar to those described above, the remainingcompounds listed in Table I were prepared.

TABLE I N N Br a)aC- N Analysis Gale (1 Found C H N C H N A mixture of25.4 g thiosemicarbazide hydrochloride and 35.6 g of1-bromo-3,3-dimethyl-2-butanone in 100 ml of absolute ethanol is heated15 to 20 hours on the steam bath. The resultant slurry is filtered andthe solid is washed with ethanol, dissolved in water and neutralizedwith sodium carbonate, giving 14.5 g of 2-aminoand 4-ethylthi- COMBATINGUNWANTED VEGETATION The novel herbicides are effective when used bothpostand pre-emergently. There is described below an illustrativeprocedure for herbicidal use of the compounds under controlledconditions in the greenhouse so as to obtain data on phytotoxic activityand selectivity.

1. Post-Emergent Use An aqueous dispersion of each active compound wasprepared by combining 0.4 gram of the compound with about 4 ml of asolvent-emulsifier mixture (3 parts of a commercial polyoxy-ethylatedvegetable oil emulsifier, one part xylene, one part kerosene) and thenadding water, with stirring, to a final volume of 40 ml.

The species of plants on which each compound was to be tested wereplanted in 4 inch pots in a greenhouse. 10 to 18 days after emergence ofthe plants,

I claim:

1. The method of combating undesired vegetation comprising applying tothe locus of the undesired vegetation a herbicidally efiective amount ofN,N'- dimethyl-N '-(5-tert.butyl-6H-l ,3 ,4-thiadiazin-2- yl)urea.

2. The method of combating undesired vegetation comprising applying tothe locus of the undesired vegetation a herbicidally effective amount ofN-methyl-N'-

2. The method of combating undesired vegetation comprising applying tothe locus of the undesired vegetation a herbicidally effective amount ofN-methyl-N''-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)urea.
 3. The methodof combating undesired vegetation comprising applying to the locus ofthe undesired vegetation a herbicidally effective amount ofN-ethyl-N''-methyl-N-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)urea.
 4. Themethod of combating undesired vegetation comprising applying to thelocus of the undesired vegetation a herbicidally effective amount ofN-allyl-N''-(5-tert.butyl-6H-1,3,4-thiadiazin-2-yl)-N''-methylurea.